Keys
The total number of keys on the keyboard.
The more keys provided in the design, the wider the instrument's own range, the more notes it can play without resorting to octave shift or transposition. On the other hand, this characteristic directly affects the dimensions and cost, and an extensive range is not required so often. Therefore,
88 -key instruments corresponding to a full-size classical piano keyboard are quite rare. But compact models with only
25 keys(2 octaves), on the contrary, are popular: for the purposes for which MIDI keyboards are used, this is often quite enough. Other common options are the
49 -key (4 octave) and
61 -key (5 octave) models; somewhat less common are
32 and
37 keys.
Aftertouch
The presence of the aftertouch function in the keyboard (aftertouch). The essence of this function is to track the pressure force on the key after it is pressed. In fact, this means that in models with aftertouch, you can control the sound not only due to the force and speed of pressing the key, but also due to the change in pressure on it after pressing; this gives additional features and allows you to use various specific tricks of the game. The specific ways of changing the sound “tied” to aftertouch can be different, depending on the synthesis settings set: for example, when recording a guitar part, you can tie a small change in tone to this function and imitate string bending, when recording a saxophone, change the volume of notes, and etc.
Relatively inexpensive models use a common sensor to monitor aftertouch, which monitors the average force of pressure on all keys pressed; in more advanced ones, separate sensors are installed for each key.
MIDI in
Input for receiving MIDI signals from an external device such as an optional keyboard or other controller, sequencer, etc. For MIDI signals, see “MIDI Out”; here we note that such signals received at the
MIDI In input can be mixed with signals from the keyboard and output via MIDI Out or another interface of a similar purpose, or they can be sent unchanged to the MIDI Thru output. It is worth looking for a device with this input if you plan to build a complex from several MIDI signal sources and intend to use the keyboard as an intermediate link in such a system.
MIDI out
A specialized output for transmitting MIDI signals to an external device — a sequencer, a computer sound card (if there is a MIDI In input), etc.
MIDI signals are a kind of "digital notation": they tell which key was pressed, with what force and for how long, and also carry information about various additional parameters: timbre, tempo, key, etc. To convert such signals a "ready" sound requires an external sequencer (software or hardware).
Note that despite its specialized purpose, the
MIDI Out output is not mandatory for modern MIDI keyboards: MIDI signals can also be transmitted via other interfaces, such as USB or Bluetooth (see the relevant paragraphs). So it makes sense to specifically look for a keyboard with such a connector if you plan to connect it to equipment with a MIDI In input.
Connectable pedals
The maximum number of pedals that can be connected to the keyboard at the same time.
Pedals are used as additional controls to change various keyboard settings. The “classic of the genre” in this sense is the sustain pedal (see “Sustain”) — if the device has
one connector for pedals, then this will almost certainly be the input for just such a pedal. Keyboards are produced, where there
are 2 or more such inputs — in addition to sustain, you can connect pedals to them for other adjustments and effects (in particular, changing the volume).
